Steerable modular drilling assembly

Abstract

In general, the present invention provides a modular drilling assembly having a module for contactless power and data transfer over a nonconductive gap between rotating and non-rotating members of a steering module. The gap usually contains a non-conductive fluid, such as drilling fluid, or oil for operating hydraulic devices in the downhole tool. The downhole tool in one embodiment is a modular drilling assembly wherein a drive shaft is rotated by a downhill motor to rotate a drill bit attached to the bottom end of the drive shaft. A substantially non-rotating sleeve around the drive shaft includes at least one electrically-operated device. The drilling assembly is modular in that it includes at least one steering module at the bottom end of the drilling assembly that has at least one steering device module that provides power to the force application member. A power and data communication uphole of the steering module provides power to the steering module and data communication between the drilling assembly and the surface.

What is claimed is:  
     
       1. A modular drilling assembly for drilling a wellbore, comprising: 
       a steering module at a bottom end of said drilling assembly, said steering module including a substantially non-rotating member outside a rotating member, said non-rotating member including at least one steering device having a pluggable power unit that provides power to a force application member to cause said force application member to extend radially outward from said drilling assembly to exert pressure on the wellbore;  
       a drill bit carried by said steering module for drilling said wellbore.  
     
     
       2. The modular drilling assembly of  claim 1  further comprising an electrical power generation module uphole of said steering module for providing electrical power to said steering module. 
     
     
       3. The modular drilling assembly of  claim 1 , wherein said pluggable power unit includes a motor, a pump and hydraulic fluid for supplying said hydraulic fluid under pressure to operate said force application member. 
     
     
       4. The modular drilling assembly of  claim 1 , wherein said steering module further includes an inductive coupling device for transferring power between said non-rotating and rotating members. 
     
     
       5. The modular drilling assembly of  claim 1  further comprising at least one module containing at least one sensor for providing measurements for determining a parameter of interest relating to the drilling of the wellbore. 
     
     
       6. The modular drilling assembly of  claim 5 , wherein said at least one sensor is selected from a group consisting of (i) an inclination sensor; (ii) a formation evaluation sensor; and (iii) a sensor for determining a physical condition of said drilling assembly. 
     
     
       7. The modular drilling assembly of  claim 1  further comprising a module uphole of said steering module that is selected from a group consisting of (i) a module containing at least one sensor for determining drilling direction of the wellbore; (ii) a module containing a battery; (iii) a module containing memory to store data downhole; (iv) a module containing at least a resistivity sensor and a gamma ray sensor; (v) a module containing at least one logging-while-drilling sensor; and (vi) a module containing a mud motor for rotating said drill bit. 
     
     
       8. The modular drilling assembly according to  claim 1 , wherein said pluggable power unit electrically plugs into a secondary electronic circuit carried by said non-rotating member. 
     
     
       9. The modular drilling assembly according to  claim 8 , wherein said power unit is disposed in a recess in said non-rotating member. 
     
     
       10. A modular drilling assembly comprising a steering module having a substantially non-rotating member operatively coupled to a rotating member, a plurality of interchangeable modules coupled to a drill string, wherein each of the plurality of interchangeable module and the steering module include at least one coupling for intrechangably coupling to one or more other modules of the plurality of interchangeable modules, and a drill bit coupled to a distal end of the drilling assembly. 
     
     
       11. The modular drilling assembly of  claim 10 , wherein the at least one coupling is a plug coupling. 
     
     
       12. The modular drilling assembly of  claim 10 , wherein the plurality of interchangeable modules includes at least one of a directional module, a power module, a communications module, a sensor module, and a control module. 
     
     
       13. The modular drilling assembly of  claim 10 , wherein the steering module includes an inductive coupling device for transferring power between the non-rotating and rotating members. 
     
     
       14. The modular drilling assembly of  claim 10 , wherein at least one of the plurality of interchangeable modules is located uphole of the steering module and is selected from a group consisting of (i) a module containing a battery, (ii) a module containing memory to store data downhole; (iii) a module containing a resistivity sensor and a gamma ray sensor; (iv) a module containing at least one logging-while-drilling sensor; and (v) a module containing a mud motor for rotating the drill bit. 
     
     
       15. The modular drilling assembly of  claim 12 , wherein the power module is disposed in a recess in the non-rotating member. 
     
     
       16. A modular steering assembly for use in a drilling assembly, the modular steering assembly comprising 
       a steering module coupled to the drilling assembly, the steering module having a substantially non-rotating member operatively coupled to a rotating member;  
       one or more modules interchangeably coupled to the steering module; and  
       a dill bit coupled to the steering module.  
     
     
       17. The modular steering assembly of  claim 16  further comprising one or more force application modules interchangeably coupled to the steering module and adapted to selectively extend in a generally radial direction from the steering module to contact a wellbore wall. 
     
     
       18. The modular steering assembly of  claim 16 , wherein the one or more modules includes a sensor module having a sensor for measuring at least one parameter of interest. 
     
     
       19. The modular drilling assembly of  claim 18  wherein the sensor is selected from a group consisting of (i) an inclination sensor; (ii) a formation evaluation sensor; and (iii) a sensor for determining a physical condition of the drilling assembly. 
     
     
       20. The modular drilling assembly of  claim 16  further comprising a control module for controlling the steering module, the control module being selectively locatable along the drilling assembly. 
     
     
       21. The modular steering assembly of  claim 17  further comprising a power module that provides power to the force application module. 
     
     
       22. A steerable drilling assembly, comprising: 
       a drill string comprising a drill bit coupled to a distal end of the drill string, and  
       a plurality of interchangeable modules disposed at several locations along the drill string, the plurality of interchangeable modules further comprising;  
       a steering module having a substantially non-rotating sleeve operatively coupled to a rotating sleeve, the steering module being disposed at a first location on the drill string;  
       a directional module at a second location on the drill string for determining drilling direction; and  
       a power module at a third location on the drill string for providing power to the steering module,  
       wherein each module in the plurality of interchangeable modules includes at least one connector adapted to allow each module in the plurality of interchangeable modules to be relocated to any of the several locations.  
     
     
       23. The steerable drilling assembly of  claim 22 , wherein the plurality of interchangeable modules further comprises at least one of: 
       a communications module at a fourth location on the drill string for transferring power and data between modules of the plurality of modules;  
       a sensor module at a fifth location on the drill string for sending at lease a physical characteristic of the steerable drilling assembly; and  
       a control module at a sixth location on the drill string for controlling the steering module.